In recent years, attention has been focused on an optical image measurement technique of forming an image representing the surface morphology or internal morphology of a measurement object by using a light beam emitted from a laser light source or the like. Because this optical image measurement technique does not have invasiveness to human bodies unlike an X-ray CT device, it is expected to apply this technique particularly in the medical field.
Patent Document 1 discloses an optical image measurement device configured in a manner that: a measuring arm scans an object by using a rotary deflection mirror (Galvano mirror); a reference mirror is disposed to a reference arm; at the outlet thereof, such an interferometer is used that the intensity of a light appearing due to interference of light fluxes from the measuring arm and the reference arm is analyzed by a spectrometer; and the reference arm is provided with a device gradually changing the light flux phase of the reference light in non-continuous values.
The optical image measurement device disclosed in Patent Document 1 uses a method of so-called “Fourier Domain OCT (Optical Coherence Tomography).” That is to say, the morphology of a measurement object in the depth direction (z-direction) is imaged by applying a beam of a low-coherence light to the measurement object, acquiring the spectrum intensity distribution of the reflected light, and subjecting the acquired distribution to Fourier transform.
Furthermore, the optical image measurement device described in Patent Document 1 is provided with a Galvano mirror that scans with a light beam (a signal light), thereby being capable of forming an image of a desired measurement target region of a measurement object. Because this optical image measurement device scans with the light beam only in one direction (x-direction) orthogonal to the z-direction, a formed image is a two-dimensional tomographic image in the depth direction (z-direction) along the scanning direction (the x-direction) of the light beam.
Further, Patent Document 2 discloses a technique of scanning with a signal light in both the horizontal and vertical directions to thereby form a plurality of two-dimensional tomographic images in the horizontal direction and, based on the plurality of tomographic images, acquiring and imaging three-dimensional tomographic information of a measurement range. A method for three-dimensional imaging is, for example, a method of arranging and displaying a plurality of tomographic images in the vertical direction (referred to as stack data or the like), and a method of forming a three-dimensional image by subjecting a plurality of tomographic images to a rendering process.
Further, Patent Document 3 discloses a configuration of using such an optical image measurement device in the ophthalmic field.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 11-325849    [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2002-139421    [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2003-543